U.S. patent application number 09/901321 was filed with the patent office on 2002-01-24 for process and apparatus for finishing a magnetic slider.
Invention is credited to Boutaghou, Zine-Eddine.
Application Number | 20020009949 09/901321 |
Document ID | / |
Family ID | 22814407 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020009949 |
Kind Code |
A1 |
Boutaghou, Zine-Eddine |
January 24, 2002 |
Process and apparatus for finishing a magnetic slider
Abstract
A process for finishing a disc drive slider in which a pressure
generator applies multiple pressures to the back surface of one
slider while the front surface of the one slider contacts a lapping
surface to form a finished front surface of the slider. The slider
is part of a substrate having multiple unfinished sliders formed in
it. An etch process is used to etch trenches in the substrate
aligned between the sliders and to form webs joining the sliders
together. After the sliders are finished by lapping, the webs are
removed to separate the sliders. The multiple sliders are
conveniently held together during the finishing process and the
etching process avoids damage to the sliders.
Inventors: |
Boutaghou, Zine-Eddine;
(Vadnais Heights, MN) |
Correspondence
Address: |
David C. Bohn
WESTMAN CHAMPLIN & KELLY
International Centre
900 South Second Avenue, Suite 1600
Minneapolis
MN
55402-3319
US
|
Family ID: |
22814407 |
Appl. No.: |
09/901321 |
Filed: |
July 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60218262 |
Jul 13, 2000 |
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Current U.S.
Class: |
451/5 ;
G9B/5.036; G9B/5.052; G9B/5.078; G9B/5.094; G9B/5.229 |
Current CPC
Class: |
G11B 5/3103 20130101;
B24B 37/048 20130101; G11B 5/3166 20130101; G11B 5/3903 20130101;
G11B 5/1871 20130101; G11B 5/102 20130101; G11B 5/60 20130101; G11B
5/3163 20130101; B24B 49/16 20130101; Y10T 29/49052 20150115; G11B
5/3116 20130101; G11B 5/3173 20130101; Y10T 29/49048 20150115; B24B
49/10 20130101; B24B 49/04 20130101 |
Class at
Publication: |
451/5 |
International
Class: |
B24B 049/00 |
Claims
What is claimed is:
1. A process for finishing a disc drive slider, comprising: A.
providing a substrate having multiple unfinished sliders formed
therein, each slider having front and back surfaces; B. using a
microstructure etch process to etch trenches in the substrate
aligned between the sliders and to form webs joining the sliders
together; C. applying multiple pressures from a multiple pressure
generator to the back surface of one slider while the front surface
of the one slider contacts a lapping surface to form a finished
front surface; and D. removing the webs.
2. The process of claim 1 wherein the microstructure etch process
comprises reactive ion etching.
3. The process of claim 1 wherein each slider includes an
electrical lap guide (ELG), and E. providing feedback from the ELG
on the one slider to the multiple pressure generator to control the
approach of the front surface to the lapping surface.
4. The process of claim 3 wherein each slider includes a
magnetoresistive (MR) transducer with a stripe height (SH) and F.
controlling the applied pressures to adjust the stripe height.
5. The process of claim 3 wherein each slider includes an inductive
transducer with a throat height (TH) and F. controlling the applied
pressures to adjust the throat height (TH).
6. The process of claim 1 wherein the multiple sliders are lapped
independently of one another.
7. The process of claim 6 wherein the multiple sliders are lapped
sequentially.
8. The process of claim 6 wherein the multiple sliders are lapped
simultaneously.
9. The process of claim 1 wherein the webs hold the sliders
together and each trench stress-isolates each slider from an
adjacent slider during the lapping.
10. The process of claim 1 wherein the webs hold the sliders
together while the trenches reduce transverse mechanical support of
each slider during the lapping.
11. The process of claim 1 where the grooves are defined by
selective masking of the substrate.
12. The process of claim 1 wherein the etching is directional
etching.
13. The process of claim 1 wherein the webs are removed in step D
by reactive ion etching.
14. The process of claim 1 wherein the substrate is a single
crystal material.
15. The process of claim 13 wherein the single crystal material is
doped silicon.
16. An apparatus for finishing a disc drive slider, comprising: a
multiple pressure generator adapted to apply multiple pressures to
the back surface of a first disc drive slider that is joined by
webs to adjacent disc drive sliders in a disc drive slider
substrate; a holding fixture for restraining the adjacent disc
drive sliders; a lapping surface arranged to lap a front surface of
the first disc drive slider; and a feedback circuit providing
feedback from electrical lap guides (ELGs) in the first disc drive
slider to the multiple pressure generator to control the approach
of the front surface to the lapping surface.
17. The apparatus of claim 16 wherein the multiple pressures are
individually controlled by the feedback from the electrical lap
guides.
18. The apparatus of claim 16 wherein the holding fixture applies a
vacuum to the adjacent disc drive sliders.
19. An apparatus for finishing a disc drive slider, comprising: a
holding fixture for holding a disc drive slider substrate including
a first disc drive slider in contact with a lapping surface; and
means for applying multiple pressures to the back side of the first
disc drive slider during lapping, and for controlling the multiple
pressures by feedback from electrical lap guides in the first disc
drive slider.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority benefits from U.S.
Provisional Application 60/218,262 titled "Stripe height control
using independent controlled sliders and method to separate sliders
from bars with deep reactive etching," filed Jul. 13, 2000
FIELD OF THE INVENTION
[0002] The present invention relates generally to sliders for use
in magnetic storage drives. In particular, this invention relates
to methods and apparatus for finishing a disc drive slider that
include lapping a surface of a disc drive slider.
BACKGROUND OF THE INVENTION
[0003] During the fabrication of magnetic heads for use in magnetic
data storage applications, an array of transducers and auxiliary
circuits are fabricated on a common substrate in a deposition of
metallic and non-metallic layers. The array is then cut up into
smaller bars, with each bar including a row of multiple read/write
heads. The bars are then lapped to adjust an average stripe height
(SH) of magnetoresistive (MR) transducers in the bar, the average
throat height (TH) of inductive transducer in the bar, or both. The
auxiliary circuits in the bars are electrical lap guides (ELGs)
that sense the progress of the lapping process. Each electrical lap
guide has an electrical resistance that increases as material is
removed by lapping. Lapping is stopped automatically when the
average stripe height and/or average throat height are within
acceptable limits. After the lapping process is complete, the bars
are cut up into individual read/write heads or sliders using
diamond saws.
[0004] The process of lapping a solid bar has a limited ability to
adjust only the average stripe height or average throat height for
all the sliders formed in the bar. There are remaining undesired
variations in individual stripe height or throat height among the
sliders in a bar.
[0005] As higher recording densities are being introduced, there is
a need for better control than this average control, particularly
in the case of stripe height. It is, however, inconvenient and
expensive to handle individual sliders in a lapping operation
because of their small size.
[0006] A process and apparatus are needed that can handle bars of
substrate with multiple sliders in each bar, while controlling
lapping to individually or independently control stripe height for
each slider.
SUMMARY OF THE INVENTION
[0007] Disclosed is a process and apparatus for finishing a disc
drive slider. The slider is part of a substrate bar having multiple
unfinished sliders formed in it. An etch process is used to etch
stress-isolating trenches in the substrate aligned between the
sliders and to form webs joining the sliders together. The
apparatus includes a pressure generator that applies multiple
pressures to the back surface of one individual slider while the
front surface of the one individual slider contacts a lapping
surface to form a finished front surface of the slider.
[0008] After the sliders are finished by lapping, the webs are
removed to separate the sliders. The webs flexibly hold the
multiple sliders together in a fixture during the lapping process
while allowing the individual sliders to move independently. The
pressures applied to each individual slider can be independently
controlled, allowing for improved control of the stripe height
(SH), the throat height (TH) or both of each sldier. The etching
process avoids damage from the use of diamond saws.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 illustrates an embodiment of a disc drive.
[0010] FIG. 2 illustrates an unfinished substrate including
multiple unfinished disc drive sliders.
[0011] FIG. 3 illustrates an unfinished substrate with a selective
masking layer.
[0012] FIG. 4 illustrates an unfinished substrate with etched
trenches.
[0013] FIG. 5 illustrates an unfinished slider with the selective
masking layer removed.
[0014] FIG. 6 schematically illustrates an apparatus applying
multiple pressures to an unfinished slider during a lapping
process.
[0015] FIG. 7 illustrates a finished substrate including finished
sliders.
[0016] FIG. 8 illustrates a cross sectional view of a slider with
an inductive transducer and a layer including a magnetoresistive
(MR) transducer.
[0017] FIG. 9 illustrates a cross sectional view that is transverse
to the view shown in FIG. 8 of the layer including a
magnetoresistive transducer (MR).
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0018] In the present invention, a bar of multiple disc drive
sliders has trenches etched between individual sliders using
etching. The etching is controlled using a selective mask, and the
etching is stopped before it completely cuts through the bar,
leaving a web that keeps the sliders flexibly joined together for
convenient handling during subsequent lapping operations. The use
of etching avoids the use of diamond saws which can leave
contamination in the form of chips and can also damage the
sliders.
[0019] A pressure generator applies multiple pressures to the back
surface of one individual slider while the front surface of the one
individual slider contacts a lapping surface to form a finished
front surface of the slider. The lapping can be automatically
controlled by feedback from electric lap guides in the one slider
being lapped. The slider being lapped is able to respond
independently to the pressures applied to it because the trenches
provide stress isolation between the individual sliders. The webs
flex to allow the slider being lapped to move independently of
adjacent sliders.
[0020] After the sliders are individually finished by lapping, the
webs are removed to separate the sliders, preferably using masking
and etching.
[0021] In FIG. 1, an embodiment of a disc drive 100 is illustrated.
Disc drive 100 includes a disc pack 126 having storage surfaces 106
that are typically layers of magnetic material. The disc pack 126
includes a stack of multiple discs and the read/write head assembly
includes a read/write transducer or slider 110 for each stacked
disc. Disc pack 126 is spun or rotated as shown by arrow 107 to
allow read/write head assembly 112 to access different rotational
locations for data on the storage surfaces 106 on the disc pack
126.
[0022] Read/write head assembly 112 is actuated to move radially,
relative to the disc pack 126, as shown by arrow 122 to access
different radial locations for data on the storage surfaces 106 of
disc pack 126. Typically, the actuation of read/write head assembly
112 is provided by a voice coil motor 118. Voice coil motor 118
includes a rotor 116 that pivots on axle 120 and an arm 114 that
actuates the read/write head assembly 112. Disc drive 100 includes
electronic circuitry 130 for controlling the operation of the disc
drive and transferring data in and out of the disc drive.
[0023] FIG. 2 illustrates a substrate 20 in an unfinished condition
including multiple unfinished disc drive sliders 22 arranged in a
bar shape. Each disc drive slider 22 includes a front surface 24
which is lapped in a subsequent finishing process while pressure or
force is applied to a back surface 26 (not visible in FIG. 2) of
each slider 22. Each disc drive slider 22 is formed from a slider
substrate and various selectively deposited layers of materials
that form a read/write head and electrical lap guides(s) in the
deposited layers.
[0024] FIG. 3 illustrates the substrate 20 with a selective masking
layer 26 applied to the front surfaces 24 of the sliders 22. The
masking layer 26 is lithographically patterned to define masking
grooves 28 which are not covered by the masking layer 26. The
masking layer 26 is formed of a material that is resistant to
erosion by etching.
[0025] FIG. 4 illustrates the substrate 20 after deep trenches 32
have been etched in substrate 20 using a microstructure etching
process. Reactive ion etching (RIE), ion beam chemical dry etch,
ion milling or other known microstructure etching (micromachining)
techniques can be used. Etching processes are known, for example,
from Handbook of Thin Film Technology, IOP Publishing Company 1997
(CD-ROM).
[0026] The position and size of trenches 32 are defined by the
masking grooves 28 and aligned between the individual sliders 22. A
directional etching process is preferred in etching trenches 32 in
order to accurately reproduce the masking grooves and etch deep
trenches 32. The substrate 20 can be formed of a single crystal
material such as doped silicon. The etching process is stopped or
controlled to etch trenches 32 only partially through the substrate
20, forming webs 34 that join the sliders 22 together. Webs 34 are
thick enough to hold the sliders 22 together during a subsequent
lapping operation, and thin and flexible enough to allow each
slider 22 to mover responsive to pressure somewhat independently of
the adjacent sliders 22.
[0027] FIG. 5 illustrates the unfinished slider 20 with the
selective masking layer 26 removed after the etching process is
complete.
[0028] FIG. 6 schematically illustrates a process of applying
multiple pressures 36 to an unfinished slider 22 during a lapping
process. In FIG. 6, a portion of the substrate 20 of FIG. 5 is
illustrated with the same reference numerals being used in FIG. 6
that are used in FIG. 5. The bar-shaped substrate 20 made up of
multiple unfinished sliders 22 joined together by webs 34 is placed
between a lapping surface 42 and a multiple pressure generator 38.
Multiple pressure generator 38 generates multiple pressures 36 that
are applied to the back side 26 of one of the sliders 22 as
illustrated. Multiple pressures 36 can be each individually
controlled based on electrical feedback 46 from an electrical lap
guide controller or circuit 44. Electrical lap guide controller 44
is connected to electrical lap guides (ELGs) 40 that are disposed
in the unfinished slider 22 that is being lapped. The front surface
24 of the slider 22 is in contact with lapping surface 42 while
controlled pressure is applied to back surface 26. A finished front
surface is formed by lapping at front surface 24 based on feedback
from the electrical lap guides (ELGs) 40. Feedback from the ELGs 40
controls the approach of the front surface 24 to the lapping
surface 42. The individual pressures 36 can be adjusted in real
time to change the profile of pressure applied from front-to-back
and left-to-right to vary the lapping rate in different regions of
the front surface 24. The stripe height (SH), the throat height
(TH) or both of each individual slider 22 are precisely controlled
using feedback from the electrical lap guides 40. The electrical
lap guides 40 are explained in more detail below in connection with
FIG. 9.
[0029] The multiple sliders 22 can be lapped independently of one
another. This can be done sequentially with a single pressure
generator 38. While the lapping is going on at one slider 22, the
backsides of adjacent sliders 22 can be held by a fixture 10 with
openings 45 that subject adjacent sliders 22 to a vacuum to
conveniently hold the bar-shaped substrate 20 in place during the
lapping operation.
[0030] Alternatively, the multiple sliders 22 can be lapped
simultaneously using multiple pressure generators 38 and multiple
ELG controllers 44. When simultaneous lapping is done, the
substrate 20 is held in place by mechanically engaging the webs 34
on an alternate mounting fixture with arms 12 inserted under the
webs 34 as illustrated.
[0031] The webs 34 hold the sliders 22 together and each trench 32
stress-isolates each slider 22 from an adjacent slider 22 during
the lapping. The webs 34 hold the sliders 22 together while the
trenches 32 reduce transverse mechanical support of each slider 22
during the lapping.
[0032] After each of the sliders 22 in substrate 20 has been
through the lapping process illustrated in FIG. 6, a finished
substrate 20 as illustrated in FIG. 7 results.
[0033] FIG. 7 illustrates a finished substrate 20 including
finished sliders 23 that include a finished (lapped) front surface
25. The finishing of the sliders having been completed, the webs 34
are removed. Webs 34 can be removed by etching as illustrated in
dashed lines in FIG. 7.
[0034] FIG. 8 illustrates a partial cross sectional view of a
slider 58 with an inductive write transducer 50 and a layer 66
including a magnetoresistive (MR) transducer and electrical lap
guides (ELGs). The cross sectional view in FIG. 8 is perpendicular
to a bottom surface 60 that is part of the lapped surface. The
portion of the slider 58 that is illustrated is a portion near the
trailing edge of the slider 58. Slider 58 is formed on a substrate
52 in a conventional manner using thin film processing techniques.
The inductive transducer 50 includes an inductive transducer throat
62 with a throat height 64. Lapping of surface 60 (as described
above in connection with FIG. 6) adjusts the height of the
inductive throat 62 and also the height of a magnetoresistor and
electrical lap guides in layer 66. The arrangement of the
magnetoresistor and electrical lap guides in layer 66 is explained
in more detail below in connection with FIG. 9.
[0035] FIG. 9 illustrates a cross sectional view that is transverse
to the view shown in FIG. 8 of the layer 66. Layer 66 includes a
magnetoresistive transducer (MR) 72 and electrical lap guides 70.
As the bottom surface 60 is lapped (as illustrated in FIG. 6), the
stripe height 74 of the magnetoresistive transducer 72 changes, and
also the electrical resistance of the electrical lap guides 70
changes as they are eroded away by the lapping process. When the
desired lap depth is acheived at dotted line 76 as indicated by lap
guide resistances, the lapping process is stopped. The stripe
height 74 is controlled by the applied pressures during lapping as
explained above in connection with FIG. 6. The throat height (TH)
64 is also controlled or adjusted by the applied pressures during
lapping.
[0036] In summary, a process for finishing a disc drive slider (22,
23) is disclosed. A substrate (20) has multiple unfinished sliders
(22) formed in it, each slider (22) has a front surface (25) and a
back surfaces (26). An etch process is used to etch trenches (32)
in the substrate (20), aligned between the sliders (22) and to form
webs (34) joining the sliders (22) together. A multiple pressure
generator (38) applies pressures (36) to the back surface (26) of
one slider (22) while the front surface (24) of the one slider (22)
contacts a lapping surface (42) to form a finished front surface
(25). The webs (34) are removed to separate the finished disc drive
sliders (26).
[0037] It is to be understood that even though numerous
characteristics and advantages of various embodiments of the
invention have been set forth in the foregoing description,
together with details of the structure and function of various
embodiments of the invention, this disclosure is illustrative only,
and changes may be made in detail, especially in matters of
structure and arrangement of parts within the principles of the
present invention to the full extent indicated by the broad general
meaning of the terms in which the appended claims are expressed.
For example, the masking and etching may vary depending on the
particular application for the slider while maintaining
substantially the same functionality without departing from the
scope and spirit of the present invention. In addition, although
the preferred embodiment described herein is directed to a slider
for a disc drive, it will be appreciated by those skilled in the
art that the teachings of the present invention can be applied to
other systems, like tape drive and magneto-optical drives, without
departing from the scope and spirit of the present invention.
* * * * *